α-keto peracids and methods for producing and using the same

ABSTRACT

The present invention provides α-keto peracids and methods for producing and using the same. In particular, α-keto peracids are useful as antimicrobial agents.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/860,680, which was filed Apr. 11, 2013 and a continuation of U.S.patent application Ser. No. 13/898,126, which was filed on May 20, 2013.U.S. patent application Ser. No. 13/860,680 was a continuation of U.S.patent application Ser. No. 12/618,605 (now U.S. Pat. No. 8,426,634),which was filed on Nov. 13, 2009, entitled “α-Keto Peracids and MethodsFor Producing and Using the Same,” and claimed the benefit of U.S.Provisional Patent Application No. 61/199,944, which was filed on Nov.20, 2008. U.S. patent application Ser. No. 13/898,126, was acontinuation of U.S. patent application Ser. No. 12/760,940 (now U.S.Pat. No. 8,445,717), which was filed Apr. 15, 2010, entitled “α-KetoAlkylperacids and Methods for Producing and Using the Same,” and acontinuation-in-part of U.S. patent application Ser. No. 12/618,605 (nowU.S. Pat. No. 8,426,634), which was filed on Nov. 13, 2009 and claimsthe benefit of U.S. Provisional Patent Application No. 61/199,944, whichwas filed on Nov. 20, 2008. This application claims priority to and thebenefit of each of the foregoing applications, all of which areincorporated herein by reference.

FIELD OF INVENTION

The present invention relates to α-keto alkylperacids and methods forproducing and using the same.

BACKGROUND

Human and mammalian health is impacted by the spread of microbialorganisms such as viruses, bacteria, and fungi. Microbial organismscontinue to cause a variety of sicknesses and ailments. In the wake ofwidespread microbial organism infections, the public has become evenfurther concerned with sanitization, both of person and property.Consequently, there has been an extensive research on the development ofsuitable antimicrobial compositions, in particular of antimicrobialcompositions that provide immediate and residual kill of microbialorganisms.

Currently, there exist several compositions and methods for reducingand/or eliminating microbial organisms from various surfaces.Conventional antimicrobial cleansing products such as hard surfacecleaners and surgical disinfectants are typically formulated to providebacteria removal during washing. Only a few such products have beenshown to provide a residual effectiveness against Gram-positivebacteria; however, even such compositions provide only limited residualeffectiveness against Gram-negative bacteria. By “residualeffectiveness,” it is meant that the subject antimicrobial controlsmicrobial growth on a substrate by either preventing growth of microbesor engaging in continuous kill of microbes for some period of timefollowing the washing and/or rinsing process.

Furthermore, many conventional antimicrobial compositions haveunpleasant odor or are chemically harsh and can cause irritation.Moreover, most conventional antimicrobial compositions are relativelyineffective against vegetative bacteria that are “dormant.” Vegetativebacteria are bacteria or microogranisms that can grow and reproduce inrich, moist soil where many nutrients are available. The activelygrowing bacteria in these conditions are referred to as “vegetativecells.” Many types of bacteria and fungi can flourish under theseconditions. Some examples of bacteria and fungi that can activelyreproduce in this kind of soil are Bacillus, Streptomyces, Pseudomonas,Micrococcus, Mycobacterium, and Clostridium. Mycobacterium tuberculosiscan cause the disease tuberculosis, and Colstridium botulinum can causebotulism poisoning.

When soil nutrients or moisture are depleted, bacteria from the genus ofBacillus and Clostridium produce an endospore inside each vegetativecell. Once the vegetative cell (active bacteria) no longer has enoughnutrients or moisture to survive, it releases the endospore. Theendospore can remain viable for very long periods. When the rightconditions return for growth, the endospore creates another vegetativecell, and the bacteria becomes active again. Some fungi produce sporesin a similar fashion.

Therefore, there is a need for antimicrobial compositions that areeffective against vegetative microbial organisms. There is also a needfor antimicrobial compositions that do not have unpleasant odor.

SUMMARY

Some aspects of the invention provide α-keto alkylperacids and methodsfor producing and using the same. Such methods typically comprisecontacting an α-keto alkylcarboxylic acid or a salt thereof with anoxidizing agent without any significant stirring and under conditionssufficient to produce the α-keto alkylperacid. While a variety ofoxidizing agents can be used in such methods, typically the oxidizingagent comprises hydrogen peroxide, barium peroxide, sodium carbonateperoxide, calcium peroxide, sodium perborate, lithium peroxide,magnesium peroxide strontium peroxide, zinc peroxide, potassiumsuperoxide, or a mixture thereof. In some embodiments, the reactiontemperature is about 10° C. or less. In other embodiments, the reactiontemperature ranges from about −30° C. to about 10° C.

Methods of the invention can be used to produce a wide variety of α-ketoalkylperacids. In some aspects of the invention, the α-keto alkylperacidis of the formula:HOO—C(═O)—C(═O)—R   Ior a salt thereof, where R is alkyl of at least two carbon atoms.

In some embodiments, R is C₂-C₂₀ alkyl. Within these embodiments, insome instances, R is C₂-C₁₀ alkyl. In some cases, R is selected from thegroup consisting of ethyl, isopropyl, propyl, butyl, isobutyl,sec-butyl, pentyl, isopentyl, neopentyl, and n-hexyl.

Other aspects of the invention provide methods for reducing the amountof microbe on a surface. Such methods typically include contacting thesurface with an antimicrobial solution comprising an effective amount ofa compound of Formula I.

In some embodiments, the microbe comprises vegetative bacteria. Withinthese embodiments, in some instances the microbe comprises bacterialspores, mycobacteria, gram-negative bacteria, vegetative gram-positivebacteria, or a combination thereof.

Still in other embodiments, the antimicrobial solution further compriseshydrogen peroxide.

Yet in other embodiments, the antimicrobial solution comprises at least40 ppm of the compound of Formula I.

Still other aspects of the invention provide methods for reducing thenumber of infectious vegetative bacteria on a substrate. Such methodsinclude contacting the substrate with an antimicrobial solutioncomprising an effective amount of a compound of Formula I.

Yet other aspects of the invention provide methods for preventing and/orreducing bacteria-related diseases in a mammal that result from themammal's contact with a bacteria-infected substrate. Such methods caninclude contacting the substrate with a composition comprising of acompound of Formula I.

Other aspects of the invention provide antimicrobial products comprisinga compound of Formula I.

In some embodiments, the antimicrobial product is a household careproduct. Exemplary house hold care products include, but are not limitedto, hard surface cleaners, deodorizers, fabric care compositions, fabriccleaning compositions, manual dish detergents, automatic dishdetergents, floor waxes, kitchen cleaners, and bathroom cleaners. Insome instances, the antimicrobial product is selected from the groupconsisting of hard surface cleaners, deodorizers, fabric carecompositions, fabric cleaning compositions, manual dish detergents,automatic dish detergents, floor waxes, kitchen cleaners, bathroomcleaners, and combinations thereof.

Yet in other embodiments, the antimicrobial product is a medical devicedisinfectant.

Still in other embodiments, the amount of compound of Formula I that ispresent in the antimicrobial product is about 100 ppm or less.

Other aspects of the invention provide a method for reducing the amountof microbe on a surface, said method comprising contacting the surfacewith an antimicrobial solution comprising an effective amount of acompound of Formula I.

In some embodiments, the microbe comprises vegetative bacteria. In otherembodiments, the microbe comprises bacterial spores, mycobacteria,gram-negative bacteria, vegetative gram-positive bacteria, or acombination thereof. In one particular embodiment, the microbe comprisesbacterial spores.

Still in other embodiments, the antimicrobial solution further compriseshydrogen peroxide. Typically, the antimicrobial solution comprises atleast 40 ppm of α-keto alkylperacid. Alternatively, the antimicrobialsolution comprises about 4,000 ppm or less, typically 1,000 ppm or less,often 500 ppm or less, more often 100 ppm or less, and still more often50 ppm or less amount of the compound of Formula I.

The half-life of compound of Formula I in the antimicrobial solutiontypically is about 120 days or more, often about 180 days or more, andmore often about 360 days or more.

Yet other aspects of the invention provide a method for reducing thenumber of infectious vegetative bacteria on a substrate comprisingcontacting the substrate with an antimicrobial solution comprising aneffective amount of a compound of Formula I. Other aspects of theinvention provide a method for reducing the number of bacterial sporeson a substrate comprising contacting the substrate with an antimicrobialsolution comprising an effective amount of a compound of Formula I.

Further aspects of the invention provide methods for preventing and/orreducing bacteria-related diseases in a mammal that result from themammal's contact with a bacteria-infected substrate. Such methodscomprise contacting the substrate with a composition comprising acompound of Formula I prior to allowing the mammal to come in contactwith the substrate.

Still other aspects of the invention provide an antimicrobial productcomprising a compound of Formula I. In some embodiments, the product isa household care product. Within such embodiments, in some cases thehouse hold care product is selected from the group consisting of hardsurface cleaners, deodorizers, fabric care compositions, fabric cleaningcompositions, manual dish detergents, automatic dish detergents, floorwaxes, kitchen cleaners, bathroom cleaners, and combinations thereof. Inother embodiments, the antimicrobial product is selected from the groupconsisting of hard surface cleaners, deodorizers, fabric carecompositions, fabric cleaning compositions, manual dish detergents,automatic dish detergents, floor waxes, kitchen cleaners, bathroomcleaners, and combinations thereof. Antimicrobial products of theinvention can be used in a wide variety of settings including, but notlimited to, in health care facilities such as hospitals, rehabilitation,assisted living facilities, etc.

In other embodiments, the antimicrobial product is a medical devicedisinfectant. Still in other embodiments, the antimicrobial product isused as a disinfectant for aseptic filling equipment. Yet in otherembodiments, the antimicrobial product is used in an aseptic foodprocessing system. In other embodiments, the antimicrobial product isused as a disinfectant for biofilms in water systems. Still in otherembodiments, the antimicrobial product is used as a disinfectant forwaste water treatment.

In some embodiments, the amount of compound of Formula I present in theantimicrobial product is about 100 ppm or less. Still in otherembodiments, the half-life of a compound of Formula I is at least 20days.

BRIEF DESCRIPTION OF THE DRAWING(S)

FIG. 1 shows graph of efficacy of peroxy α-keto pyruvic acid against C.Difficile with or without a catalyst.

FIG. 2 is a graph showing efficacy of peroxy α-keto butyric acid againstC. difficile at various concentrations.

FIG. 3 is a graph showing comparison of effectiveness against C.difficile between peroxy pyruvic acid and peroxy α-ketobutyric acid.

FIG. 4 is a table showing effectiveness of antimicrobial activities ofvarious carboxylic acids and peroxy α-keto carboxylic acids againstvarious microorganisms.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Some aspects of the invention provide α-keto alkylperacids and methodsfor producing and using the same. As used herein, the terms “α-ketoalkylperacid” and “α-keto alkylperoxyacid” are used interchangeablyherein and refer to a compound of the formula: HOO—C(═O)—C(═O)—R, or asalt thereof, where R is alkyl of at least two carbon atoms. The termalkyl refers to a saturated linear monovalent hydrocarbon moiety of twoto twenty, typically two to ten, and often two to eight carbon atoms ora saturated branched monovalent hydrocarbon moiety of three to twenty,typically three to ten, and often three to eight carbon atoms. Exemplaryalkyl group include, but are not limited to, ethyl, n-propyl, 2-propyl,tert-butyl, pentyl, and the like.

Peracids or peroxyacids refer to carboxylic acids in which the acidic—OH group has been replaced by an —OOH group. They are strong oxidizingagents and are generally unstable. They are most often used as oxidizingagents in various chemical reactions. Peroxy acids are generally notvery stable even in solution and decompose to their correspondingcarboxylic acid and oxygen. Because most peracids decompose relativelyquickly under ambient conditions, they are typically not used for anyother purposes except in chemical reactions. Even then, many peroxyacidsare synthesized just prior to their use. Some peroxyacids, for example,meta-chloroperoxybenzoic acid (MCPBA), are somewhat stable at a lowertemperature as long as they are not in a pure form. Pure MCPBA can bedetonated by shock or by sparks. It is therefore, commercially sold as amuch more stable mixture that is less than 72% pure.

Typically, peroxyacids are prepared by electrolytic oxidation ofordinary carboxylic acids or by using a transition metal catalyst and anoxidizing agent or by using a very strong oxidizing agent. Inelectrolytic oxidation, typically a high current density must be used toform the peroxyacid in good yield. Such use of a high current densitytypically increases the cost of producing peroxyacids.

Peroxyacids can also be produced using a transition metal catalyst andan oxidizing agent or simply by using a strong oxidizing agent.Unfortunately, use of a strong oxidizing agent in and of itself createspotentially dangerous conditions and increases the high cost ofperoxyacid production. And use of a transition metal catalyst render theresulting peroxyacid often contaminated with the transition metal.

Some methods of the invention for producing α-keto alkylperacids includecontacting an α-keto alkylcarboxylic acid or a salt thereof with anoxidizing agent without any significant stirring and under conditionssufficient to produce the α-keto alklperacid. Typically, the reactioncondition comprises non-stirring conditions where a mixture of theα-keto alkylcarboxylic acid and the oxidizing agent is simply allow tostand without any stirring. As used herein, unless the context requiresotherwise, the term “stir” or “stirring” refers to agitating or act ofcausing a mixing of the reagents by using an external force such as byusing a mechanical stirrer, a magnetic stirrer, a shaker, or any othermechanical, electrical, magnetic, or manual force including simplymixing the reagents manually (e.g., by stirring or shaking).

Surprisingly and unexpectedly, the present inventors have found that bycontacting an α-keto alkylcarboxylic acid and an oxidizing agent andletting the mixture stand without any significant mixing, a good yieldof the corresponding α-keto alkylperoxyacid can be produced. Generally,the yield of the reaction is at least 5%, typically at least 8%, andoften at least 12%.

It should be noted that the yield of the α-keto alkylperoxyacid isaffected by a variety of reaction conditions and reagents used. One ofthe factors influencing the yield of α-keto alkylperoxyacid is thereaction temperature. Generally, the rate of reaction increases as thetemperature increases. However, a higher reaction temperature can alsoincrease the yield of side-product(s) and/or decomposition of the α-ketoalkylperoxyacid that is formed. Therefore, the reaction temperature istypically kept at about 10° C. or below, often at about 4° C. or below,and more often at about −10° C. or below.

The concentration of the reagents can also affect the rate and the yieldof α-keto alkylperoxyacid. The initial concentration of the oxidizingagent is generally about 12 M or less, typically about 7 M or less, andoften about 1 M or less.

The reaction time can also affect the yield of α-keto alkylperoxyacid.Typically the reaction time ranges from about 4 hrs to about 12 hrs,often from about 6 hrs to about 8 hrs, and more often from about 10 hrsto about 12 hrs.

Methods of the invention are applicable to a wide variety of α-ketoalkylcarboxylic acids. Generally any α-keto alkylcarboxylic acid can beused to produce the corresponding α-keto alkylcarboxylic acid. Exemplaryα-keto carboxylic acids include, but are not limited to, α-keto butyricacid, α-keto valeric acid, α-keto hexanoic acid, etc.

Exemplary oxidizing agents that are useful in methods of the inventioninclude, but are not limited to, hydrogen peroxide, barium peroxide,sodium carbonate peroxide, calcium peroxide, sodium perborate, lithiumperoxide, magnesium peroxide strontium peroxide, zinc peroxide,potassium superoxide, and the like.

When describing a chemical reaction, the terms “treating,” “contacting,”and “reacting” are used interchangeably herein, and refer to adding twoor more reagents under appropriate conditions to produce the indicatedand/or the desired product. It should be appreciated that the reactionwhich produces the indicated and/or the desired product may notnecessarily result directly from the combination of reagents which wereinitially added, i.e., there may be one or more intermediates which areproduced in the mixture which ultimately leads to the formation of theindicated and/or the desired product.

The reaction is generally conducted in an aqueous solution. Othersolvents, such as an organic solvent can also be used in addition to orin place of the aqueous solution. Because it is inexpensive andcommercially available in an aqueous solution, typically hydrogenperoxide is used as an oxidizing agent.

The ratio of oxidizing agent to α-keto alkylcarboxylic acid typicallyranges from about 0.5:1 to about 2:1, often about 2:1 to about 6:1.

While various reaction parameters are disclosed herein, it should beappreciated that the scope of the invention is not limited to theseparticular reaction parameters. Utility

While the use of peroxy alkylcarboxylic acids as an oxidizing agent in achemical reaction is generally known, surprisingly and unexpectedly, thepresent inventors have discovered that α-keto alkylperoxyacids haveparticularly useful and potent antimicrobial properties. Accordingly,compounds and compositions or the invention can be used as adisinfectant. As used herein, the term “disinfection” refers to removal,destruction, killing, or reducing of at least a significant portion of apathogenic microorganism population from a surface of an object.Typically, methods, compounds and compositions of the invention can beused to reduce at least about 90%, often at least about 95%, more oftenat least about 98%, still more often at least about 99.9% and most oftenall of the microorganism population from a surface. Moreover, incontrast to most commercial antimicrobial compounds that are used asdisinfectants, α-keto alkylperoxyacids have been found to be alsoeffective against bacterial spores.

Disinfection is often done to protect the integrity of bacteriologicaltest results (for example, test done for health screening of patients)and/or to prevent the occurrence and spread of disease resulting frominability to control the pathogenic microorganism population. As usedherein, the term “microorganism” includes bacteria, virus, fungi, algae,prion, and other pathogenic organisms known to one skilled in the art.Typically, the term microorganism refers to bacteria. Physicalsterilization—for example, applying steam or other gas via pressurizedautoclave—is generally not feasible for disinfection of large spaces andsurfaces or sensitive medical equipment. In addition, physicalsterilization is inapplicable for protecting the integrity of testresults. Moreover, physical sterilization cannot be used on delicate ortemperature-sensitive instruments and devices.

Human and mammalian health is impacted by the spread of microbialentities at home, school, work and in the environment generally. Asstated above, conventional methods of disinfection or cleaning andsanitizing various equipments and areas require very high temperaturesup to 185° F. or the use of a relatively harsh antimicrobial compound.Unfortunately, the majority of conventional chemical disinfecting agentsare useful for reducing only gram-positive bacteria.

Bacteria found on human skin are typically divided into two groups,namely, resident and transient bacteria. Resident bacteria areGram-positive bacteria that establish as permanent microcolonies on thesurface and outermost layers of the skin. Such bacteria play afundamental role in preventing the colonization of other, more harmfulbacteria and fungi. Transient bacteria are bacteria that are not part ofthe normal resident of the flora of the skin. Rather, transient bacteriaare deposited when airborne contaminated material lands on the skin orwhen contaminated material is brought into physical contact with suchbacteria. Transient bacteria are typically divided into two subgroups:Gram-positive and Gram-negative. Gram-positive bacteria includepathogens such as Staphylococcus aureus, Streptococcus pyogenes andClostridium botulinum. Gram-negative bacteria include pathogens such asSalmonella, Escherichia coli, Klebsiella, Haemophilus, Pseudomonasaeuginosa, Proteus and Shigella dysenteriae. Gram-negative bacteria aregenerally distinguished from Gram-positive bacteria via the existence ofan additional protective cell membrane in the former, which oftenresults in Gram-negative bacteria being less susceptible toconventional, topical antibacterial actives.

As stated above, there exist several compositions and methods forreducing and/or eliminating the formation of bacteria and/or viruses.For example, it is well known that the washing of hard surfaces, food(e.g., fruit or vegetables) and skin, especially the hands, withantimicrobial or non-medicated soap, is effective against viruses andbacteria. Often removal of the viruses and bacteria is due to thesurfactant activity of the soap and the mechanical action of the washprocedure, rather than the function of an antimicrobial agent. Thus, itis recommended that people wash frequently to reduce the spread ofviruses and bacteria. However, many conventional products and methods ofsanitization, including washing, fail to address the dilemma ofsanitization “on the go,” that is to say, when a consumer is removedfrom the benefit of running water. Those skilled in the art haveattempted to resolve this dilemma via the incorporation of antimicrobialagents into disinfecting lotions, cleansing wipes and the like. Sucharticles reduce the need for water during or following the applicationof the subject composition.

Other conventional antimicrobial cleansing products include deodorantsoaps, hard surface cleaners, and surgical disinfectants. Thesetraditional, rinse-off antimicrobial products have been formulated toprovide bacteria removal during washing. A few such products, includingantimicrobial soaps, have also been shown to provide a residualeffectiveness against Gram-positive bacteria, but provide limitedresidual effectiveness against Gram-negative bacteria. By “residualeffectiveness,” it is meant that the antimicrobial agent controlsmicrobial growth on a substrate by either preventing growth of microbesor engaging in continuous kill of microbes for some period of timefollowing the washing and/or rinsing process. To address the dilemma oflimited residual efficacy against Gram-negative bacteria, some havesought to incorporate high levels of alcohol and/or harsh surfactantsinto contemporary antimicrobial products, which have been shown to causedryness and irritation to skin tissues.

While hundreds of different compounds registered with the EPA, claimingto effectively disinfect or sanitize against various microbes, the vastmajority, if not all, of the registered compounds have one or more ofthe following undesirable characteristics: will leave a residue on thetreated surface (which must be wiped away); are flammable (thus,considered a DOT hazard material subject to extra transport and storagerestrictions and costs); are corrosive, to some degree, to the surfacesto which they are applied; are toxic to animals (human and non-human);and are, thus, not considered environmentally-friendly; a concept thathas been coined in many industries, broadly, as being “Green.” Inparticular, the following undesirable characteristics have beenidentified with various currently-used chemical disinfectants: Ethanoland Isopropanol are slow in their germicidal action on surfaces, fairlyineffective against Gram positive bacteria and are not effective againstspores. In addition, these are flammable compounds and require one tofollow hazardous shipping requirements. Formaldehyde has a pungentlyirritating odor and is toxic. Phenols, which are basic to a number ofpopular disinfectants at high dilutions, are toxic, are flammable, andare not effective in ordinary usage against spores. Quartenary ammoniumcompounds often leave residues, are neutralized by anionic detergents,and are not tuberculocidal or sporicidal even at high concentrations.Hypochlorites are strong oxidizing agents and may function asdisinfectants at the proper concentrations, but are, as a whole,corrosive to metals and can be dangerous to handle. Iodophors likewisemay function as disinfectants at the proper concentrations, but leavestains (residue) and are often less effective if any appreciable amountof protein is present. Most heavy metal based antimicrobial agents aretoxic and more bacteriostatic than bacteriocidal. Peroxides are widelyused to clean skin surfaces and wounds, but they have negligibleantimicrobial activity.

Microorganisms, including bacteria, fungi, algae, viruses, prions andother such microbial entities, can be found within any growth conditionor environment where life exists. While many varieties of bacterialmicrobes are useful or ‘friendly’ to their animal-hosts, others proveirritating and troublesome—yet, relatively harmless—to manage theirpopulations. Many strains of microbes pose a very serious—and oftenlethal—risk to the health of co-existent animal populations. Decreasingthose troublesome, very serious, and lethal microbial populations undernon-sterile conditions requires the use of an antimicrobial agent.Different bacteria show varying degrees of resistance toward aparticular disinfectant. Prions tend to be the most-resistant of allmicrobial entities to antimicrobial agents. Bacterial spores andmycobacteria are generally considered to be the most resistant forms ofthe bacteria, followed by Gram-negative bacteria, which are generallyconsidered to be more resistant than vegetative Gram-positive bacteriasuch as the staphylococci and enterococci.

Some aspects of the invention provide antimicrobial compositions andmethods for using the same. In some embodiments, the antimicrobialcompositions include an α-keto alkylperoxyacid. Surprisingly andunexpectedly, the present inventors have discovered that suchcompositions are also effective in disinfecting bacterial spores.Compositions of the invention can optionally include one or moreadditional antimicrobial agent (e.g., hydrogen peroxide), a pH neutraldiluting solvent (e.g., water), or a combination thereof. Typically, thediluting solvent is a pH neutral liquid solvent adaptable for dissolvingthe α-keto alkylperoxyacid, e.g., water.

Other aspects of the composition can also include an additional agentthat can attack the protective protein layer of microbes (for example,non-enveloped viruses or spores) and/or an additional agent that candissolve the lipid nature of the envelopes or membranes of the microbes.Suitable additional antimicrobial agents include organic acids,peroxides, alcohols, and ethers.

In some embodiments, the concentration of α-keto alkylperoxyacid insolution is about 1,000 ppm or less, typically 500 ppm or less, often400 ppm or less, more often 200 ppm or less, and most often 100 ppm orless. Yet in other embodiments, the composition comprises at least about2.5% (v/v) of α-keto alkylperoxyacids.

As stated above, compositions of the invention can also comprise asecond antimicrobial agent. In some cases, the amount of secondantimicrobial agent can be at least 3% (v/v). Suitable secondantimicrobial agents include those mentioned herein as well as otherantimicrobial agents known to one skilled in the art. In one particularembodiment, the second antimicrobial agent is hydrogen peroxide.

Compositions of the invention can also include one or more of theadditional agents. Exemplary additional agents include, but are notlimited to, organic acids (such as dichloracetic acid for proteindisruption), other peroxides (for protein disruption), alcohols (such asdiacetone alcohol for membrane disruption), and ethers (such as butyleneglycol monomethyl ether for membrane disruption). Compositions of theinvention have shown to be generally non-toxic and non-flammable.Compositions of the invention also evaporate relatively rapidly from asurface-of-interest leaving only an acceptable level of measurableresidue.

In some embodiments of the invention, compositions of the invention areused to disinfect a gram-positive bacteria, a gram-negative bacteria, abacterial spore, or a combination thereof. Unlike other conventionallyknown antimicrobial agents that are commercially used, compositions ofthe invention have been shown to be effective in not only disinfectinggram-positive bacteria, but also in gram-negative bacteria, andbacterial spores.

In many instances, compositions of the invention provide at least 6-logorder complete kill or reduction of vegetative bacteria when applied toa surface. In other instances, compositions of the invention provide atleast 5-log reduction of bacterial spores. Often, compositions of theinvention provide a “complete kill” of the bacterial population atop thesurface such that any functional bacteria remaining atop thesurface-of-interest is/are not capable of re-populating to a measureablelevel, thereby rendering any toxicity or pathogenic functionality of theoriginal bacterial population effectively null.

Compositions of the invention can be applied in aerosol form such asspraying from a bottle containing liquid antimicrobial agent onto asurface. Once applied to the surface, the composition is adapted toevaporate to dryness (to the touch), typically within about 10 to about30 minutes while leaving acceptable levels (if any) of measureableresidue on the surface, such acceptable levels are generally set basedon the surface on which the disinfectant is used. Compositions of theinvention are typically non-flammable and of very low toxicity allowingthem to be shipped as a non-hazardous chemical, per DOT guidelines.Moreover, solutions comprising the compositions of the invention oftenhave low surface tension and are effective in the presence of proteins.

Compositions of the invention can be used to disinfect clean rooms,hospitals, veterinary and dental offices, laboratories (e.g., generalmedical/veterinary/dental, Q.A. manufacturing, new productdevelopment/R&D, and other laboratories), medical equipment and devices,household surfaces, sports equipment, as well as any suitable objects orsurface so desired. Some of the characteristics of compositions of theinvention include, but are not limited to, effectiveness at highdilutions in the presence of organic matter; a broad spectrum ofantimicrobial activity-effectiveness against gram-positive,gram-negative bacteria, spores, viruses, and fungi); stable under theconditions of transport, storage and use; homogeneity; solubility inwater, fats, and oils for good penetration into microorganisms; lowsurface tension for penetration into cracks and crevices; minimumtoxicity-lack of acute and chronic toxicity, mutagenicity,carcinogenicity, etc.; capable of being applied with no residue after adesired period of time has passed; pleasant or minimal odor;non-flammable; low or no impact to plants and animals; and low cost.

Other aspects of the invention provide products that comprise theantimicrobial compositions of the present invention, as well ascombinations of such products. Indeed, the combined and systematic useof products containing the antimicrobial compositions of the inventionserves to eradicate microorganisms for a longer period of time andprevent their spread.

Some embodiments of the invention provide personal care productscomprising the antimicrobial compositions disclosed herein. Suitablepersonal care products comprising the antimicrobial compositiondisclosed herein include, but are not limited to, hand soaps, handsanitizers, body washes, mouth washes, toothpastes, shower gels,shampoos, body lotions, deodorants, nasal sprays, foot care, vaginalcare and/or wash, pet care and combinations thereof.

In yet other aspects of the present invention, the personal careproducts disclosed herein take the form of a wipe product, particularlysuitable for wiping or drying the face or hands. In such instance, theantimicrobial compositions of the invention are typically embedded orimpregnated into the wipe product.

Still in other aspects of the present invention, the personal careproduct disclosed herein takes the form of a tissue or towel, alsosuitable for wiping or drying the face or hands. In another aspect ofthe present invention, the personal care product takes the form of afeminine napkin and/or a diaper. In another aspect of the presentinvention, the personal care product takes the form of a first aidantiseptic for irritated, injured, or acne-affected skin and/or for preor post surgical use.

Yet other aspects of the invention provide antimicrobial compositionsdisclosed herein that are incorporated into one or more household careproducts. Indeed, suitable household care products for purposes of theinvention include, but are not limited to, hard surface cleaners,deodorizers, fabric care compositions, fabric cleaning compositions,manual dish detergents, automatic dish detergents, floor carecompositions, kitchen cleaners or disinfectants, bathroom cleaners ordisinfectants and combinations thereof.

In other aspects of the invention, the household care product takes theform of a wipe or towel, suitable for household cleaning and/or care. Insome embodiments of the invention, the household care products cancomprise certain adjunct ingredients. Exemplary adjuncts include, butare not limited to, detersive enzymes, builders, bleaching agents,bleach activators, transitional metal bleach catalysts, oxygen transferagents and precursors, soil release agents, clay soil removal and/oranti-redeposition agents, polymeric dispersing agents, brightener,polymeric dye transfer inhibiting agents, chelating agents, anti-foamagents, alkoxylated polycarboxylates, fabric softeners, perfumes,carriers, hydrotropes, processing aids, dyes or pigments, solvents forliquid formulations, solid fillers, detersive surfactants andcombinations thereof.

Yet still in other aspects of the invention, the antimicrobialcompositions disclosed herein can be incorporated into a skin careproduct. In such aspects of the invention, the skin care productincorporates a dermatologically acceptable carrier to facilitate safetransfer of the antimicrobial composition disclosed herein to thedesired area of the skin. In some embodiments, the skin care product caninclude certain adjunct ingredients. Suitable adjuncts include, but arenot limited to, other antimicrobial and antifungal actives, surfactants,desquamation actives, anti-acne actives, anti-wrinkle actives,anti-atrophy actives, anti-oxidants, radical scavengers, chelators,flavonoids, anti-inflammatory agents, anti-cellulite agents, topicalanesthetics, tanning actives, sunscreen actives, conditioning agents,thickening agents, detackifying agents, odor control agents, skinsensates, antiperspirants and mixtures thereof. Other suitable adjunctingredients are well known to one skilled in the art. See, for example,U.S. Pat. No. 6,294,186, which is incorporated herein by reference inits entirety.

Additional objects, advantages, and novel features of this inventionwill become apparent to those skilled in the art upon examination of thefollowing examples thereof, which are not intended to be limiting. Inthe Examples, procedures that are constructively reduced to practice aredescribed in the present tense, and procedures that have been carriedout in the laboratory are set forth in the past tense.

EXAMPLES Example 1

This example illustrates one method of testing the antimicrobial effectsof compounds of the invention.

Kill Time Test

This is a test performed to demonstrate log reduction values over timefor a disinfectant against selected bacteria, fungi, and/or mold. Arepresentative list of the organisms tested include, but are not limitedto, Bacillus subtilis, Bacillus atrophaeus, Bacillus thuringiensis,Staphylococcus aureus, Salmonella cholerasuis, Pseudomonas aeruginosa,Aspergillus niger, and Trichophyton mentagrophytes. The followingexemplifies one procedure derived from disinfectant test methods foundin guidelines of the Association of Official Analytical Chemists (AOAC)to meet “log reduction criteria” established by the U.S. EnvironmentalProtection Agency (EPA) and U.S. FDA for certain applications: (1) Atube of the sample-disinfectant is placed into a waterbath fortemperature control and allowed to equilibrate; (2) Once the tube hasreached temperature, it is inoculated to achieve a concentration ofapproximately 10⁶ CFU/mL; (3) At selected time points (generally fivepoints are used including zero) aliquots are removed and placed into aneutralizer blank; (4) Dilutions of the neutralizer are made andselected dilutions plated onto agar; (5) Colonies are enumerated and logreductions are calculated.

Preparation of Bacterial Suspensions

In order to obtain observable significant reductions (on the order of10₆) of surface bacteria, a high number of viable CFU/in² must beavailable for treatment on the surface to be disinfected. Since asubstantial number of organisms die during the drying process, it isnecessary to start with bacterial suspensions that exceed theconcentration desired on the final surface. It has been found that asuspension prepared from an agar plate that has been stored refrigeratedover-night yields a relatively even surface film upon application anddrying. The cool overnight storage of the agar plate reduces the surfacetension of the subsequent suspension. Suspensions were prepared insterile skim milk medium (SM) by harvesting the organism from the agarplate using a sterile cotton swab and vigorously vortex mixing toachieve homogeneity. A viable concentration of 10⁸-10⁹ CFU/mL was used.Most non-fastidious organism suspensions can be retained in the coolerfor several days, and were used as long as enumeration demonstratedsatisfactory viability.

Test Surface Preparation

Glass cover slips (e.g., 25 mm²) were used as the test surface for thisprocedure. Sterile slides were used for this procedure. Slides weresterilized by placing them in layers separated by filter paper (e.g.,Whatman #1) and placing them in an aluminum envelope then baking at150-170° C. for 1-2 hours.

The microorganism film was prepared by dispensing 20 μL of suspensiononto a sterile slide and spreading the suspension drop over the surfaceof the slide. A sterile inoculating needle that has been bent in theshape of a hockey stick was used. The slide were placed on the pins of asterile disposable plastic 96 well inoculating head that had small dropsof sterile water placed onto some of the pins to help hold the slide inplace during preparation. The suspension was spread as near to the edgesof the slide as possible without touching the edge. The drop wasrespread once more when necessary without over spreading. The suspensionwas allowed to dry uncovered at room temperature. Inoculated slides wereused as soon as possible, often the same day to minimize loss ofviability.

Disinfectant Application

Care was taken during treatment application to assure consistencybetween slides and experiments. Disinfectants were applied to inoculatedslides with an air brush (e.g., Iwata revolution R4500) from a distanceof 20-30 cm and a 12-18 psi setting of the compressor output regulator.Travel time for a treatment pass was about 1 ft/sec. Methods wereadjusted in order to maintain consistent application between slides.Slides were air dried uncovered at room temperature.

Enumeration

The effectiveness of treatments was evaluated by enumeration of thesurviving bacteria on the slide. The bacteria were removed from theslide and the disinfectant was neutralized by immersion of the slide inLetheen broth (LB). The bacteria were then plated in appropriatedilutions. A positive control was included for comparison to assessefficacy.

To enumerate viable organisms on a slide, the slide was placed into a 50mL centrifuge tube containing 20 mL of LB. The tube was vigorouslyshaken for 5 seconds and then vortexed for 5 seconds. Mixing step wasrepeated once. The LB was diluted in peptone, and was plated on anappropriate agar to attain countable dilutions. The LB tube (fordecreased limit of quantitation) and agar plates were incubatedovernight at the appropriate atmosphere and temperature.

Typically, for an effective disinfectant, about 50 μL of the LB tube waslogarithmically spiral plated (DF=20) onto the appropriate agar. In somecases, LB was plated at higher dilutions, e.g., transferred 90 μL of LBto 9 mL of peptone and spiral plated 50 μL (DF=2000).

The CFU/slide was calculated using the spiral plater counting tables andmultiplying by the dilution factor. Viability loss due to disinfectionwas determined by comparing treated slide values with the untreatedpositive control.

Example 2

Various concentrations of peroxy pyruvic acid generated from differentcompositions of a mixture from pyruvate, hydrogen peroxide (H₂O₂), andwater were tested to determine the log reduction of Bacillus cereusspores. These spores had been incubated for 7 years and thus thepossibility of vegetative cells remaining was very low. Each sample ofdilute pyruvate and hydrogen peroxide solution noted in Table 1 wastested employing the spray test outlined above. Slides of MRSA weretreated with peroxy pyruvic acid derived from the composition of 10%pyruvate and 3% H₂O₂ as a control. The log reduction of the MRSA controlwas approximately 6-logs, there was no growth in the broth used to platefor enumeration, therefore, it was assumed that complete elimination ofthe MRSA population was accomplished. As Table 1 illustrates, peroxypyruvic acid derived from a mixture of 10% pyruvate with 3% H₂O₂resulted in a 3.5-log reduction of the B. cereus spores. However, peroxypyruvic acid derived from the composition of 5% pyruvate and 3% H₂O₂eliminated all the B. cereus spores. As in Example 1 above, the waterused in these studies is USP purified.

TABLE 2 Log Reduction of Bacillus cereus spores. Positive B. cereusControl (BC 2) log = 5.7 Positive MRSA Control (Sta 25) log = 8.3Solution No. Organism % H₂O₂ % Pyruvate Log Reduction 2 MRSA 3 10 >5.7*1 BC 2 1 10 1.1 2 BC 2 3 10 >3.5 3 BC 2 1 5 0.4 4 BC 2 3 5 5.7* 5 BC 2 —10 1.1 6 BC 2 — 5 0.8 *Total kill/destruction of microbes, i.e. nogrowth in Letheen broth tubes (3 reps).

Example 3

Peroxy pyruvic acid was synthesized as follows. Pyruvic acid was addedto hydrogen peroxide at a temperature of between −30° C. and 10° C.until a conglomerate layer formed on the bottom of the flask. Thereaction was allowed to stand without stirring until all pyruvic acidhad dissolved into solution. Formation of peroxy pyruvic acid wasconfirmed by mass spectrometer and by chemical reaction.

Example 4

The reaction of Example 3 was repeated with the addition of SulfuricAcid (H₂SO₄) as a catalyst. An ice bath was used to keep the reactioncool resulting in quantifiable amounts of perpyruvic acid production.

Example 5

Reaction of Examples 3 and 4 were repeated for α-Ketobutanoic Acid(CH₃CH₂COCOOH) and α-Ketovaleric Acid (CH₃CH₂CH₂COCOOH) to produce thecorresponding α-keto peracids.

Example 6

FIG. 1 shows efficacy of peroxy pyruvic acid against C. Difficile usingsulfuric acid catalysts and methods of Example 1 above. All efficacystudies for C. difficile were done according to the Official Method966.04 “Sporicidal Activity of Disinfectants”.

FIG. 2 shows efficacy of peroxy alpha keto butyric acid against C.Difficile.

Example 7

In another experiment, 15 ml of 30% Hydrogen Peroxide was stirred usinga stir bar while adding 0.25 ml of the Pyruvic acid in increments every1.5 minutes. In one instances, the reaction was carried out at roomtemperature and in another instances at 5° C. Titration of the resultingmixtures showed that there was no observable peracid formation.

Example 8

When preparing Peroxy-alpha-Ketobutyric Acid (POKBA) fromalpha-Ketobutyric Acid, some modifications were needed due to thephysical nature of the material. Alpha-Ketobutyric Acid is a hygroscopicsolid that melts at 30-34° C. Thus, it is often present as a mixture ofliquid and solid. The liquid was added first and this initiated thereaction after approximately 10% of the total weight had been added.This was a marked departure from the preparation of peroxypyruvic acid,in which the reaction initiates almost immediately with the firstaddition of the pyruvic acid.

As in the preparation of perpyruvic acid, the hydrogen peroxide was heldat about 4° C. When the last of the liquid alpha-Ketobutyric Acid hadbeen added, it becomes necessary to either add a solid or to add aliquid (obtained by immersing the container with the acid into a hotwater bath at 50° C. The resultant melt was then added in the samemanner as before except that, since a warm liquid was being added to acold liquid, the additions were made with greater time periods betweenthem so as to allow the temperature to re-equilibrate. In addition, uponcontact with the cold liquid some of the melted solid froze, thuscausing a small amount of solid to sink to the bottom. This solidreacted and the greater time periods between additions became necessary.

Overall, it is believed that this reaction proceeded somewhat slowerthan the perpyruvic acid synthesis, although it was essentially completewithin a week as in the case with Pyruvic acid when prepared without acatalyst.

Example 9

Pyruvic peracid (PPA) and Peroxy α-ketobutyric acid (POKBA) were testedagainst C. difficile using the ASTM E2197-02 testing method and theresults are shown on FIG. 3. As the graph shows, POKBA is significantlymore active compared to PPA. The method of testing these moleculesagainst C. difficile was designed to evaluate the ability of liquidchemical germicides to inactivate vegetative bacteria, viruses, fungi,mycobacteria and bacterial spores in the presence of a soil load on diskcarriers that represent environmental surfaces and medical devices. Itwas also designed to have survivors that can be compared to a mean of noless than three control carriers to determine if the performancestandard has been met: The test protocol did not include any wiping orrubbing action. This test method is a standard test promulgated by ASTMCommittee E35 on Pesticides and Subcommittee E35.15 on AntimicrobialAgents. The stringency in the test is provided by the use of a soilload, the microtopography of the carrier surface and the small ratio ofdisinfectant to surface area (1:5) typical for many disinfectantapplications. Thus the formulation under test is presented with areasonable challenge while allowing for efficient recovery of the testorganisms from the inoculated carriers with or without their exposure tothe test formulation. The metal disks used in the basic test are alsocompatible with a wide variety of germicidal actives and most surfacesin consumer based product manufacturing and health care facilities. Thedesign of the metal discs makes it possible to place onto each preciselymeasured volume of the test organism (28 μL) as well as the testformulation (125 μL). The inoculum is placed at the center of each diskwhereas the volume of the test formulation covers nearly the entire disksurface thus eliminating the risk of any organisms remaining unexposedto the test formulation. The relatively small ratio of 1:5 between thevolume of the inoculum and that of the test formulation closely reflectsmany field applications of liquid chemical germicides. In all testsother than those against viruses, the addition of 9.95 mL of a diluentgives a 1:200 dilution of the test formulation immediately at the end ofthe contact time. While this step in itself may be sufficient to arrestthe germicidal activity of most formulations, a Letheen Broth (LB) wasused as a specific neutralizer and diluent.

The soil load used in this test was a mixture of three types of proteins(high molecular weight proteins, low molecular weight peptides andmucous material) and consisted of a mixture of 0.5 g of tryptone, 0.5 gof BSA, and 0.04 g of bovine mucin in 10 mL phosphate buffer (pH 7.2).These solutions were prepared separately and sterilized by passagethrough a 0.22 μm pore diameter membrane filter, aliquoted and stored ateither 4° C. or −20° C. To obtain 500 μL of the inoculum for the discs,340 μL of the microbial suspension was added to 25 μL of BSA, 100 μL ofmucin, and 35 μL of tryptone stock.

Stainless Steel Disks (1 cm in Diameter and Approx. 0.7 mm Thick) wereprepared from sheets of magnetized and brushed stainless steel 10similar to that used in the manufacture of countertops. The disks weresoaked in a detergent solution for at least one hour to degrease themand then washed and sterilized by autoclaving.

C. difficile was prepared by suspending a C. difficile suspensionovernight into pre-reduced Brain heart infusion broth (BHI) and allowedto grow overnight. Inoculates from the BHI were streaked onto thesurface of a sufficient number of pre-reduced trypticase soy agar plateswith 5% sheep blood (BA) for confluent growth using a swab wetted in theprepared suspension (i.e., containing 1 mL of spore suspension). The BAplates were incubated for 14-28 days anaerobically. Afterwards, thecells were harvested from the agar by adding 3 mL of sterile distilledwater to the surface of the BA plate and suspended using a bent glassrod to suspend the cells from the plate into the water. A combinedrinsing of each plate was added into one or more 50 mL centrifugetube(s). The cells were centrifuged at 4500 rcf for 15 minutes and thesupernatant carefully discarded. These steps were repeated twoadditional times. The final 10 mL of spore suspension was heated in a65-70° C. water bath (assuring the entire tube is immersed) for 30minutes. The final concentration of spores in the suspension werechecked for the purity of the spores by preparing a 1:1000 dilution inanaerobic broth and spiral plating 50 μL onto reduced BA plates. Thespores were stored at 2-8° C. until needed.

The disks were inoculated with 25 μl, of 10⁶ C. difficile sporessuspended in the soil load and allowed to dry. Afterwards, 125 μL ofdifferent concentrations of the alpha Keto peroxy acids (AKPA) wereadded to the discs and allowed to set for 10 minutes before dilutioninto the LB neutralizer. Afterwards, the LB neutralizer was vortexed for5 seconds and 50 μL of the LB in the tube was logarithmically spiralplated (DF=20) onto the appropriate agar. Controls were treatedsimilarly as with the AKPA with the exception that water replaced theAKPA.

Example 10

Various carboxylic acids and peroxy α-keto carboxylic acids were testedagainst various microorganisms. The results are shown in FIG. 4. Aseries of methods were used for testing the microbes and are defined bythe column titles on the Table in FIG. 4. The details of these methodsare as follows:

Preparation of Bacterial Suspensions

In order to obtain observable significant reductions (on the order of10⁶) of surface bacteria, a high number of viable CFU/in² must beavailable for treatment on the surface to be disinfected. Since asubstantial number of organisms die during the drying process, it isnecessary to start with bacterial suspensions that exceed theconcentration desired on the final surface. It has been found that asuspension prepared from an agar plate that has been stored refrigeratedovernight yields a relatively even surface film upon application anddrying. The cool overnight storage of the agar plate reduces the surfacetension of the subsequent suspension. Suspensions were prepared insterile skim milk medium (SM) by harvesting the organism from the agarplate using a sterile cotton swab and vigorously vortex mixing toachieve homogeneity. A viable concentration of 10⁸-10⁹ CFU/mL istypically used. Most non-fastidious organism suspensions can be retainedin the cooler for several days, and used as long as enumerationdemonstrates satisfactory viability. Spore suspensions can be useddirectly or diluted to achieve the desired concentration of organism.

Test Surface Preparation

Sterile glass cover slips (e.g., 25 mm²) were used as the test surfacefor the spray test and the immersion test. Slides were Sterilized byplacing them in layers separated by filter paper (e.g., Whatman #1) andthen in an aluminum envelope and baking them at 150-170° C. for 1-2hours.

The organism film on the slide was prepared by dispensing 20 μL ofsuspension onto a sterile slide and spreading the suspension drop overthe surface of the slide. With a sterile inoculating needle that hasbeen bent in the shape of a hockey stick. Sometimes it is helpful torest the slide on the pins of a sterile disposable plastic 96 wellinoculating head that has had small drops of sterile water placed ontosome of the pins to help hold the slide in place during preparation. Thesuspension was spread as near to the edges of the slide as possiblewithout touching the edge. Care was taken to not allow organisms ontothe reverse side of the slide, as it will not be exposed to disinfectantwhen treated. The suspension was allowed to dry uncovered at roomtemperature. The Inoculated slides were used the same day as prepared tominimize loss of viability.

Spray Test

Disinfectants were applied to inoculated glass coverslips with an airbrush (e.g., Iwata revolution R4500) from a distance of 20-30 cm and a12-18 psi setting of the compressor output regulator. Travel time for atreatment pass was ˜1 ft/second. Treated slides were air dried uncoveredat room temperature.

Immersion Test.

Organisms were prepared on slides as indicated above. The carrier slideswith the organisms were placed in 20±2 mL of disinfectant and allow tosoak for the desired amount of time. After 10 minutes, the carrierslides were placed into LB broth and enumerate discussed below.

Organism Enumeration

The effectiveness of treatments were evaluated by enumeration of thesurviving bacteria on the slide versus positive controls which had beentreated with water. The positive controls demonstrated how manysurviving bacteria were on the carrier slides when not treated withdisinfectant. The bacteria are neutralized and removed from the slidesby votexing them in Letheen broth (LB) and then plating for counts bypipetting 50 μL of the appropriate dilutions in the LB tubes onto aplate and logarithmically spiral plating (DF) onto the appropriate agar.Also direct dilution of the original suspension was directly enumeratedto determine if there were any viability loss in the organism suspensiondue to desiccation.

AOAC 966.04 Test Against B. Subtilis

This test is applicable to testing germicides for presence or absence ofsporicidal activity against specified spore forming bacteria in varioussituations and potential efficacy as sterilizing agent. The organismtypically used for testing disinfectants for use against bacteria andbacterial spores with medical devices such as endoscopes, catheters, andetc. is B. Subtilis spores because they are known to form biofilms whichare difficult to eradicate. This is done by testing the disinfectantsfor sporicidal kill of the spores which are attached to ceramic pennycylinders.

The B. Subtilis spores were formed by inoculating nutrient agar (NA)slants and then washing growth on the slants with 10 mL of steriledeionized water and transferring to Roux bottles containing antibioticmedium #2 (AM#2) with MnSO₄. The bottles were placed in a water bath at65-70° C. water bath for 30 min. Afterwards the spore suspension wascentrifuged at ˜4500 rpm for 15 min. The supernatant was decanted andthe spores resuspended with ˜20 mL of sterile water. The centrifugationand resuspension of the spores was repeated 3× more with intermittenthomogenization. Finally the B. subtilis spore pellet was placed in a65-70° C. water bath for 30 min then resuspended in 30 mL of sterilewater. Afterwards, the suspension was streaked onto nutrient agar fordetermination of purity.

Evaluation of disinfectants against B. subtilis was done by attachingthe spores to Porcelain cylinders, 8±1 mm od, 6±1 mm id, 10±1 mm longwhich had been sterilize by incubation for 2 h in 180° C. air oven.Afterwards the penny cylinders were washed with Triton X-100 and rinsedwith water 4 times. The contaminated spores were gently placed into thedisinfectant in test tubes for 10 minutes and then removed and placedinto 10 mL±0.1 mL of LB neutralizer. The neutralizer tubes weresonicated for 5±1 minute in a room temperature water bath. Afterwards,the tube containing penny cylinders were vortexed and diluted forenumeration by the above described method. Positive controls were pennycylinders that had only been exposed to sterile water.

The foregoing discussion of the invention has been presented forpurposes of illustration and description. The foregoing is not intendedto limit the invention to the form or forms disclosed herein. Althoughthe description of the invention has included description of one or moreembodiments and certain variations and modifications, other variationsand modifications are within the scope of the invention, e.g., as may bewithin the skill and knowledge of those in the art, after understandingthe present disclosure. It is intended to obtain rights which includealternative embodiments to the extent permitted, including alternate,interchangeable and/or equivalent structures, functions, ranges or stepsto those claimed, whether or not such alternate, interchangeable and/orequivalent structures, functions, ranges or steps are disclosed herein,and without intending to publicly dedicate any patentable subjectmatter.

What is claimed is:
 1. A method for reducing the amount of microbe on anirritated, injured, or acne-affected skin comprising contacting the skinwith an antimicrobial solution comprising an effective amount of aperoxy α-ketocarboxylic acid.
 2. The method of claim 1, wherein theperoxy α-ketocarboxylic acid is selected from the group consisting ofperoxy pyruvic acid, peroxy α-ketobutyric acid, peroxy α-ketovalericacid, or combination thereof.
 3. The method of claim 1, wherein theantimicrobial solution is a personal care product selected from thegroup consisting of hand soaps, hand sanitizers, skin gels/wipes, bodywashes, mouth washes, toothpastes, shower gels, shampoos, body lotions,deodorants, nasal sprays, foot care, vaginal care and/or wash, andcombination thereof.
 4. The method of claim 3, wherein the personal careproduct is a hand sanitizer.
 5. The method of claim 3, wherein thepersonal care product is in the form of a wipe.
 6. The method of claim3, wherein the personal care product is in the form of a liquid or agel.
 7. The method of claim 3, wherein the personal care product is inthe form of a spray.
 8. The method of claim 1, wherein the antimicrobialsolution is effective against C. Difficile.
 9. The method of claim 1,wherein the antimicrobial solution is effective against gram-positivebacteria, gram-negative bacteria, bacterial spores, viruses, fungi,prions and combination thereof.
 10. The method of claim 1, wherein theamount of the peroxy α-ketocarboxylic acid present in the antimicrobialsolution is about 500 ppm or less.
 11. The method of claim 1, whereinthe antimicrobial solution further comprises an antimicrobial agent,antifungal agent, or an anti-inflammatory agent.
 12. The method of claim1, wherein the antimicrobial solution further comprises an organic acid.13. The method of claim 1, wherein the antimicrobial solution furthercomprises hydrogen peroxide.
 14. The method of claim 1, wherein theantimicrobial solution further comprises an alcohol.
 15. The method ofclaim 1, wherein the antimicrobial solution further comprises an ether.16. The method of claim 1, wherein the antimicrobial solution furthercomprises a surfactant.